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Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]17
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]18 <div class="submenu">
19 <label>libc++ Info</label>
20 <a href="/index.html">About</a>
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22
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24 <label>Quick Links</label>
Chris Lattnera535ffd2010-05-11 20:53:16 +0000[diff] [blame]25 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">cfe-dev</a>
26 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits">cfe-commits</a>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]27 <a href="http://llvm.org/bugs/">Bug Reports</a>
Howard Hinnant76e1ffc2010-05-11 20:51:20 +0000[diff] [blame]28 <a href="http://llvm.org/svn/llvm-project/libcxx/trunk/">Browse SVN</a>
29 <a href="http://llvm.org/viewvc/llvm-project/libcxx/trunk/">Browse ViewVC</a>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]30 </div>
31</div>
32
33<div id="content">
34 <!--*********************************************************************-->
35 <h1>"libc++" C++ Standard Library</h1>
36 <!--*********************************************************************-->
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]37
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]38 <p>libc++ is a new implementation of the C++ standard library, targeting
Howard Hinnantaf347342012-07-19 15:57:51 +0000[diff] [blame]39 C++11.</p>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]40
Chris Lattnerf38bc6e2010-11-16 21:40:19 +0000[diff] [blame]41 <p>All of the code in libc++ is <a
42 href="http://llvm.org/docs/DeveloperPolicy.html#license">dual licensed</a>
43 under the MIT license and the UIUC License (a BSD-like license).</p>
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]44
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]45 <!--=====================================================================-->
46 <h2 id="goals">Features and Goals</h2>
47 <!--=====================================================================-->
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]48
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]49 <ul>
Howard Hinnantaf347342012-07-19 15:57:51 +0000[diff] [blame]50 <li>Correctness as defined by the C++11 standard.</li>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]51 <li>Fast execution.</li>
52 <li>Minimal memory use.</li>
53 <li>Fast compile times.</li>
54 <li>ABI compatibility with gcc's libstdc++ for some low-level features
55 such as exception objects, rtti and memory allocation.</li>
56 <li>Extensive unit tests.</li>
57 </ul>
58
59 <!--=====================================================================-->
Marshall Clowfaa17162012-11-14 16:31:15 +0000[diff] [blame]60 <h2 id="why">Why a new C++ Standard Library for C++11?</h2>
Chris Lattner24173b82010-05-12 22:21:15 +0000[diff] [blame]61 <!--=====================================================================-->
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]62
Chris Lattner24173b82010-05-12 22:21:15 +0000[diff] [blame]63 <p>After its initial introduction, many people have asked "why start a new
64 library instead of contributing to an existing library?" (like Apache's
65 libstdcxx, GNU's libstdc++, STLport, etc). There are many contributing
66 reasons, but some of the major ones are:</p>
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]67
Chris Lattner24173b82010-05-12 22:21:15 +0000[diff] [blame]68 <ul>
69 <li><p>From years of experience (including having implemented the standard
70 library before), we've learned many things about implementing
71 the standard containers which require ABI breakage and fundamental changes
72 to how they are implemented. For example, it is generally accepted that
73 building std::string using the "short string optimization" instead of
74 using Copy On Write (COW) is a superior approach for multicore
Marshall Clowfaa17162012-11-14 16:31:15 +0000[diff] [blame]75 machines (particularly in C++11, which has rvalue references). Breaking
Chris Lattnera5058d92010-05-12 22:30:22 +0000[diff] [blame]76 ABI compatibility with old versions of the library was
Chris Lattner24173b82010-05-12 22:21:15 +0000[diff] [blame]77 determined to be critical to achieving the performance goals of
78 libc++.</p></li>
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]79
Chris Lattner24173b82010-05-12 22:21:15 +0000[diff] [blame]80 <li><p>Mainline libstdc++ has switched to GPL3, a license which the developers
81 of libc++ cannot use. libstdc++ 4.2 (the last GPL2 version) could be
Marshall Clowfaa17162012-11-14 16:31:15 +0000[diff] [blame]82 independently extended to support C++11, but this would be a fork of the
Chris Lattnerf3382492010-05-12 22:33:00 +0000[diff] [blame]83 codebase (which is often seen as worse for a project than starting a new
84 independent one). Another problem with libstdc++ is that it is tightly
85 integrated with G++ development, tending to be tied fairly closely to the
86 matching version of G++.</p>
Chris Lattner24173b82010-05-12 22:21:15 +0000[diff] [blame]87 </li>
88
89 <li><p>STLport and the Apache libstdcxx library are two other popular
Marshall Clowfaa17162012-11-14 16:31:15 +0000[diff] [blame]90 candidates, but both lack C++11 support. Our experience (and the
Howard Hinnantaf347342012-07-19 15:57:51 +0000[diff] [blame]91 experience of libstdc++ developers) is that adding support for C++11 (in
Chris Lattner24173b82010-05-12 22:21:15 +0000[diff] [blame]92 particular rvalue references and move-only types) requires changes to
93 almost every class and function, essentially amounting to a rewrite.
Chris Lattnerbfa808e2010-05-12 22:34:21 +0000[diff] [blame]94 Faced with a rewrite, we decided to start from scratch and evaluate every
95 design decision from first principles based on experience.</p>
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]96
Chris Lattner24173b82010-05-12 22:21:15 +0000[diff] [blame]97 <p>Further, both projects are apparently abandoned: STLport 5.2.1 was
98 released in Oct'08, and STDCXX 4.2.1 in May'08.</p>
99
100 </ul>
101
102 <!--=====================================================================-->
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]103 <h2 id="requirements">Platform Support</h2>
104 <!--=====================================================================-->
105
106 <p>libc++ is known to work on the following platforms, using g++-4.2 and
Howard Hinnantaf347342012-07-19 15:57:51 +0000[diff] [blame]107 clang (lack of C++11 language support disables some functionality).</p>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]108
109 <ul>
110 <li>Mac OS X i386</li>
111 <li>Mac OS X x86_64</li>
112 </ul>
113
114 <!--=====================================================================-->
115 <h2 id="dir-structure">Current Status</h2>
116 <!--=====================================================================-->
117
Howard Hinnantb0895ff2012-11-27 18:52:32 +0000[diff] [blame]118 <p>libc++ is a 100% complete C++11 implementation on Apple's OS X. </p>
Michael J. Spencerdb8a0302012-12-31 19:34:21 +0000[diff] [blame^]119 <p>LLVM and Clang can self host in C++ and C++11 mode with libc++ on Linux.</p>
Howard Hinnantd0e811a2010-05-13 20:10:39 +0000[diff] [blame]120
Howard Hinnant0cbb3a12011-09-28 15:44:39 +0000[diff] [blame]121 <p>
Howard Hinnantee7a0bf2012-07-31 21:30:28 +0000[diff] [blame]122 Ports to other platforms are underway. Here are recent test
123 results for <a href="results.Windows.html">Windows</a>
124 and <a href="results.Linux.html">Linux</a>.
Howard Hinnant0cbb3a12011-09-28 15:44:39 +0000[diff] [blame]125 </p>
126
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]127 <!--=====================================================================-->
128 <h2>Get it and get involved!</h2>
129 <!--=====================================================================-->
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]130
Howard Hinnant2481cba2011-09-30 16:58:02 +0000[diff] [blame]131 <p>First please review our
132 <a href="http://llvm.org/docs/DeveloperPolicy.html">Developer's Policy</a>.
133
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]134 <p>To check out the code, use:</p>
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]135
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]136 <ul>
Chris Lattner4b748952010-05-11 20:37:52 +0000[diff] [blame]137 <li><code>svn co http://llvm.org/svn/llvm-project/libcxx/trunk libcxx</code></li>
Howard Hinnant65451f12011-01-27 23:18:19 +0000[diff] [blame]138 </ul>
139
Howard Hinnant704f09b2011-11-17 17:14:16 +0000[diff] [blame]140 <p>
Howard Hinnant22b781b2012-11-06 21:31:37 +0000[diff] [blame]141 On Mac OS 10.7 (Lion) and later, the easiest way to get this library is to install
Howard Hinnant704f09b2011-11-17 17:14:16 +0000[diff] [blame]142 Xcode 4.2 or later. However if you want to install tip-of-trunk from here
Howard Hinnant271a1c02012-04-03 15:08:42 +0000[diff] [blame]143 (getting the bleeding edge), read on. However, be warned that Mac OS
144 10.7 will not boot without a valid copy of <code>libc++.1.dylib</code> in
145 <code>/usr/lib</code>.
Howard Hinnant704f09b2011-11-17 17:14:16 +0000[diff] [blame]146 </p>
147
Howard Hinnant65451f12011-01-27 23:18:19 +0000[diff] [blame]148 <p>
149 Next:
150 </p>
151
152 <ul>
153 <li><code>cd libcxx/lib</code></li>
154 <li><code>export TRIPLE=-apple-</code></li>
155 <li><code>./buildit</code></li>
Howard Hinnant22b781b2012-11-06 21:31:37 +0000[diff] [blame]156 <li><code>ln -sf libc++.1.dylib libc++.dylib</code></li>
Howard Hinnant65451f12011-01-27 23:18:19 +0000[diff] [blame]157 </ul>
158
159 <p>
Howard Hinnant22b781b2012-11-06 21:31:37 +0000[diff] [blame]160 That should result in a libc++.1.dylib and libc++.dylib. The safest thing
161 to do is to use it from where your libcxx is installed instead of replacing
162 these in your Mac OS.
Howard Hinnant65451f12011-01-27 23:18:19 +0000[diff] [blame]163 </p>
164
Howard Hinnant65451f12011-01-27 23:18:19 +0000[diff] [blame]165 <p>
Howard Hinnant22b781b2012-11-06 21:31:37 +0000[diff] [blame]166 To use your system-installed libc++ with clang you can:
Howard Hinnant65451f12011-01-27 23:18:19 +0000[diff] [blame]167 </p>
168
169 <ul>
170 <li><code>clang++ -stdlib=libc++ test.cpp</code></li>
Howard Hinnantaf347342012-07-19 15:57:51 +0000[diff] [blame]171 <li><code>clang++ -std=c++11 -stdlib=libc++ test.cpp</code></li>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]172 </ul>
173
Howard Hinnant22b781b2012-11-06 21:31:37 +0000[diff] [blame]174 <p>
175 To use your tip-of-trunk libc++ on Mac OS with clang you can:
176 </p>
177
178 <ul>
179 <li><code>export DYLD_LIBRARY_PATH=&lt;path-to-libcxx&gt;/lib</code>
180 <li><code>clang++ -std=c++11 -stdlib=libc++ -nostdinc++
181 -I&lt;path-to-libcxx&gt;/include -L&lt;path-to-libcxx&gt;/lib
182 test.cpp</code></li>
183 </ul>
184
Marshall Clow08a0b482012-08-22 00:57:11 +0000[diff] [blame]185 <p>To run the libc++ test suite (recommended):</p>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]186
187 <ul>
Chris Lattner4b748952010-05-11 20:37:52 +0000[diff] [blame]188 <li><code>cd libcxx/test</code></li>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]189 <li><code>./testit</code></li>
Howard Hinnantf5d76a72011-06-22 12:13:55 +0000[diff] [blame]190 <ul>
Howard Hinnant22b781b2012-11-06 21:31:37 +0000[diff] [blame]191 <li>You can alter the command line options <code>testit</code> uses
192 with <code>export OPTIONS="whatever you need"</code></li>
Howard Hinnantf5d76a72011-06-22 12:13:55 +0000[diff] [blame]193 </ul>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]194 </ul>
195
Howard Hinnant51065652012-05-20 13:03:53 +0000[diff] [blame]196 <!--=====================================================================-->
197 <h3>Notes</h3>
198 <!--=====================================================================-->
199
200<p>
201Building libc++ with <code>-fno-rtti</code> is not supported. However linking
202against it with <code>-fno-rtti</code> is supported.
203</p>
204
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]205 <p>Send discussions to the
Howard Hinnant8c217372010-05-11 19:53:34 +0000[diff] [blame]206 (<a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">clang mailing list</a>).</p>
207
Howard Hinnant56f0d5b2010-10-05 16:44:40 +0000[diff] [blame]208 <!--=====================================================================-->
Michael J. Spencerdb8a0302012-12-31 19:34:21 +0000[diff] [blame^]209 <h2>Build on Linux using CMake and libsupc++.</h2>
210 <!--=====================================================================-->
211
212 <p>
213 You will need libstdc++ in order to provide libsupc++.
214 </p>
215
216 <p>
217 Figure out where the libsupc++ headers are on your system. On Ubuntu this
218 is <code>/usr/include/c++/&lt;version&gt;</code> and
219 <code>/usr/include/c++/&lt;version&gt;/&lt;target-triple&gt;</code>
220 </p>
221
222 <p>
223 You can also figure this out by running
224 <pre>
225$ echo | g++ -Wp,-v -x c++ - -fsyntax-only
226ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
227ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../x86_64-linux-gnu/include"
228#include "..." search starts here:
229#include &lt;...&gt; search starts here:
230 /usr/include/c++/4.7
231 /usr/include/c++/4.7/x86_64-linux-gnu
232 /usr/include/c++/4.7/backward
233 /usr/lib/gcc/x86_64-linux-gnu/4.7/include
234 /usr/local/include
235 /usr/lib/gcc/x86_64-linux-gnu/4.7/include-fixed
236 /usr/include/x86_64-linux-gnu
237 /usr/include
238End of search list.
239 </pre>
240
241 Note the first two entries happen to be what we are looking for. This
242 may not be correct on other platforms.
243 </p>
244
245 <p>
246 We can now run CMake:
247 <ul>
248 <li><code>CC=clang CXX=clang++ cmake -G "Unix Makefiles"
249 -DLIBCXX_CXX_ABI=libsupc++
250 -DLIBCXX_LIBSUPCXX_INCLUDE_PATHS="/usr/include/c++/4.7/;/usr/include/c++/4.7/x86_64-linux-gnu/"
251 -DCMAKE_BUILD_TYPE=Release
252 -DCMAKE_INSTALL_PREFIX=/usr
253 &lt;libc++-source-dir&gt;</code></li>
254 <li><code>make</code></li>
255 <li><code>sudo make install</code></li>
256 </ul>
257 <p>
258 You can now run clang with -stdlib=libc++.
259 </p>
260 </p>
261
262 <!--=====================================================================-->
Howard Hinnant56f0d5b2010-10-05 16:44:40 +0000[diff] [blame]263 <h2>Design Documents</h2>
264 <!--=====================================================================-->
265
266<ul>
267<li><a href="atomic_design.html"><tt>&lt;atomic&gt;</tt></a></li>
Howard Hinnant9835d762010-11-19 01:38:58 +0000[diff] [blame]268<li><a href="type_traits_design.html"><tt>&lt;type_traits&gt;</tt></a></li>
Howard Hinnant820e0072012-07-06 00:39:38 +0000[diff] [blame]269<li><a href="http://marshall.calepin.co/llvmclang-and-standard-libraries-on-mac-os-x.html">Excellent notes by Marshall Clow</a></li>
Howard Hinnant56f0d5b2010-10-05 16:44:40 +0000[diff] [blame]270</ul>
271
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]272</div>
273</body>
Chris Lattner4b748952010-05-11 20:37:52 +0000[diff] [blame]274</html>